Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Craft,
published 1929 - 1953. All copyrights are hereby acknowledged.

This Radio Service Data Sheet for the Motovox Models 10A All-Electric
and 10E Battery-Operated "Moto-Tetradynes" is an example of
the dozens of similar schematic and alignment instruction sheets
that have been posted on RF Cafe over the years. Obtaining technical
information on most things, even readily available items, prior
to the Internet era was often very difficult - if not impossible.
Service centers had what was need provided by manufacturers
and distributors, but if you wanted to find a part number or
service data on a refrigerator, radio, lawn mower, garage door
opener, etc., and did not have the original paperwork, you were
usually out of luck. Nowadays a Web search will quite often
get you what you need thanks to people
(like me) who go to the trouble
of making the information available. The stuff doesn't just
magically appear or get posted by benevolent governmental entities.
You're welcome.

Since the intensity of signal strength delivered by the antenna
to the receiver is directly proportional to the height and effective
length and inversely proportional to the resistance of the antenna,
it is necessary to use every precaution to obtain an effective
auto-radio antenna installation. Thus, only a low-capacity shielded
lead-in should be used; also, the antenna should not come closer
than 3 ins. to any metal-work. A counterpoise antenna is used
in an automobile since no actual ground is available. The height
of the antenna is, therefore, equal to the distance between
the flat plane of the antenna and the body of the car. Consequently,
the most efficient aerial is one in which the capacity of lead-in
and aerial matches the antenna stage of the receiver, covers
the largest possible area and is as far removed as possible
from the body of the car.

The following instructions pertain to the installation of
the model 10A set. After mounting the power supply, run the
separately shielded red lead, in the reproducer, to terminal
No.3. Next, connect the red lead in the radio cable to the "B+"
terminal in the supply and the yellow lead to the "B-" terminal,
making certain that the shield of the cable is anchored by the
mounting clamp provided in the power supply. Now connect the
black, yellow-tracer lead of the tuning control along with the
yellow lead from the power supply terminal No. 2 to the ungrounded
or "hot" post of the battery. Connect the black lead from terminal
No. 1 of the power supply to the grounded battery post. Make
certain that the connecting to the battery are correct. Do not
pull forward the switch underneath the tuning control until
the receiver has been plugged into the harness, otherwise, the
power unit win be operating without a load.

Installation instructions which apply to the model 10E receiver
are as follows. Connect the yellow lead in the "B" harness to
the negative tap of the 180 V. battery (four Burgess type 2308
batteries). Next, connect the maroon lead to the"+45" tap, and
the red lead to the "+180" tap. In this line is a 1/4-A. fuse.

The sensitivity control on the model 10E set is located in
the bottom of the receiver. After tuning the set to a no-signal
position near 1,400 kc., turn the sensitivity control right,
or clockwise, to "stop," then back it, counterclockwise, until
the static level becomes very high. This is the point of maximum
sensitivity. to exceed this will result in lack of sensitivity
and A.V.C. It is recommended that this control be set just below
maximum sensitivity to reduce engine interference.

Due to the current interest in automotive radio installations
the following information concerning car antennas is furnished
through courtesy of Motometer Gauge & Equipment Co. Although
most of the late car models are equipped at the factory with
an aerial of some type, earlier cars will usually require the
services of a technician acquainted both with the technique
of handling car upholstery and the demands of good antenna design.

It is recommended that No. 14 or No. 16 mesh copper or galvanized
screen be used. Do not forget to clear the dome-light by 3 ins.
In fastening the lead-in to the screen, a No. 18 insulated wire
should be used and if the aerial is copper screen it should
be soldered around two adjacent sides so that a good electrical
connection is assured. The screen should then be securely tacked
at all points possible, making certain that it is not grounded
to any metal part of the top. Conceal the lead-in and replace
the top, soldering the end of the No. 18 wire to the short shielded
lead-in which is provided with most sets, making sure to insulate
the soldered joint well; ground the shield to some part of the
metal body. Keep the unshielded portion of the lead-in, that
is, the No. 18 rubber covered wire, as short as possible so
that the shielded lead-in actually enters, if possible, the
metal corner post. eliminating the possibility of spark pick-up
by the unshielded lead.

Top construction may be divided into the following general
classifications:

Open and Convertible. Loosen the top slightly preliminary
to putting it back and weave a No. 18 insulated wire around
the border between the top and the flap, giving in all a total
length of about 60 ft. of wire. Then bring down the lead-in
in the manner described above, and re-tighten the top.

Screen Wire Tops. Clip a 3 in. border around the top. Lace
the center screen to the edges, using raw-hide,

Standard Fabric Tops. This type of top will be found most
frequently. Use a wire screen, as described, removing it 3 ins.
from all metals.

Posted August 7, 2015

Radio Service Data Sheets

These schematics, tuning instructions, and other data are reproduced from my
collection of vintage radio and electronics magazines. As back in the era, similar
schematic and service info was available for purchase from sources such as
SAMS Photofacts, but these printings
were a no-cost bonus for readers. There are 220 Radio Service Data Sheets as of
February 2, 2018.

RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas
and reference material while performing my work as an RF system and circuit design engineer.
The Internet was still largely an unknown entity at the time and not much was available
in the form of WYSIWYG
...

All trademarks, copyrights, patents, and other rights of ownership to images and text
used on the RF Cafe website are hereby acknowledged.